Apparatus for turning noncircular work



E. R. SMITH APPARATUS FOR TURNING NONGIRCULAR WORK July 16, 1935.

I5 Sheets-Sheet 1 Filed Jain. 29, 1934 3844a"): dizz /2 July 16, 1935.RiSMlTH 2,008,474

APPARATUS FOR TURNING NONCIRCULAR WORK Filed Jan. 29,1934 3 Sheets-Sheet2 9 r Iaavz'nf died/ y 935. B SMITH 2,008,474

APPARATUS FOR TURNING NONCIRCULAR WORK Filed Jan. 29, 1954 :sSheets-Sheet 3 mined eccentricity or other Patented July 16, 1935 a a I2,008,474

Edwin R. Smith, Seneca Falls, N. Y., assignor to SenecaFalls MachineCompany, Seneca Falls, N. Y., a. corporation of MassachusettsApplication January 29,

1934;} Serial No. 708,868

9 Claims. (01. 82-18) This invention relates to machine tools such aslathes in which work of approximately circular cross section isproduced.

In some types of turned Work a slightlysmaller dimension on certaindiameters is desired. As an illustration of such work, pistons forautomobileengines are preferably of less diameter along the axis of thewrist pin than at right angles thereto. This difference in diameter isvery slight, however, being commonly only afew thousandths of an inch.The skirt of such an engine piston is also preferably slightly tapered.

Such work must be produced commercially at very high speed and it hasbeen found that the usual relieving devices as heretofore knownareunsatisfactory for such high speed work on account of the weight andinertia of the reciprocated parts-.- V h It is the general object of myinvention to provide apparatus by which slightly non-circular work maybe turned in a lathe or other similar machine tool at high speed andwith predeterirregularity of diameter.

More specifically I provide means by which slight predeterminedvariations indiameter or radius are obtained as a result of the rotarymo: tion of a cutting tool about an axis transverse to the axis of thework. 7

My invention further relates to arrangements and combinations of partswhichwill behereinafter described and more particularly pointed out inthe appended claims.

A preferred form of the invention is shown in I the drawings, in which lz r Fig. 1 isa plan view of. portions of a lathe embodying myimprovements;' 5 v Fig. 2 is a sectional front elevation, taken alongthe line 2-2 in Fig. 1;

Fig. 3 isa sectional side elevatiomtaken along the line 3-3 in Fig. 1;

Fig. 4 is an enlarged side elevation of the cutting tool used in myimproved apparatus;

Fig. 5 is an end view of the. cutting tool, looking in the direction ofthearrow 5 in Fig. .4;

Figs. 6 to 11 are diagrammatic views illustrating the operation of theinvention, and I Fig. 12 is a diagrammatic plan view to be described.

Referring to the drawings, I have shown portions of an automatic latheincluding ahead stock 20 (Fig. 1), a tailstock 2i, a chuck22, a tailcenter 23 and a piece of work W supported between the-chuck 22 and tailcenter 23.

. A tool carriage 25 is slidable lengthwise of the lathe on supportingportions of the frame F of the lathe and may be moved longitudinally ofthe lathe by the usual feed screw 21. A table isslidable transversely ofthe carriage 25 in guidewa s 3|, and may be secured in any adjustedposition in said guideways.

Arstand33 is slidable longitudinally of the machine in guideways 34(Fig. 3) on the upper surface of the table 30 and may be clamped in anyadjusted position by bolts 35 (Fig. 1). The upper surface of the table30 is preferably inclined at a slight angle as indicated in Fig. 3. a

, 3 A tool slide is slidable in guideways 4| (Fig. 1) on the stand 33and is provided with a roll 42 engaging onesideof a templet bar 43. Theopposite edge of the .bar 43 engages a bearing surface in a portion 44of the stand 33, and a cap plate 45 (Fig. 3) holds the templet bar infirm contact with the portion 44. The endof the bar 43 is secured to anyconvenient fi xedportion of the machine, by which connection the bar isheld from longitudinal movement. The roll is pressed against the templetbar 43 by one or more springs 41 (Fig.

3) mountedin pockets 48 in the stand 33 and engaging a projectingportion 49 of the. slide 40. The roll 42 is thus held in firm contactagainst one edge of the templet bar 43, and any varia: tion inthel'width of the bar will cause a corresponding movement of. the toolslide 40 toward or from the work W. l Q

By varying. the shape of the templet bar, the diameter of the work maybe increased or decreasedas desired as a turning operation thereonproceeds. If the sides of the templet bar are both straight but at aslight angle, uniformly tapered work will be produced. .1 A. rotarycutter 50 is mounted in a tool spindle 5|? (Fig. .3) rotatable inanti-friction thrust bear- =ings .54 and in the tool slide 40.Preferably the axis of the spindle 5| intersects the ams of the work W..Suitable provision such as a cup washer 56 and coil spring 51 may beprovided to exclude dirt at the end of the tool spindle ad- :jacent thework.

A worm gear 60 is secured to the spindle 5| and is driven by a worm 6|mounted on a sleeve 62 supported in rollerthrust bearings in the toolslide 40. A driving shaft 63 is slidable in the sleeve 62 but' is keyedto provide a driving con- -nection therewith. The driving shaft 63 isconconnecting shaft 66 to a countershaft 61 driven surface.

relation that the cutter rotates-through one tooth space for each halfrevolution of the work W.

The cutter 5i! resembles end mill, with teeth 70 each formed with atransverse cutting end These cutting surfaces may be in a planetransverse to the axis of the cutter but are preferably very slightlycrowned for purposes of clearance. This crowning of the cutting edges isindicated in exaggerated formfor the purposes of clearness in Fig. 12.

Having described the mechanical construction of my improvedapparatus-the method of operation thereof'to'produce non-circular workwill now be described. I

The slight variations in diameter are produced as a result of thegradual upward movement of the cutting teeth, by which movements eachcutting edge very slightly approaches the axis of the work W andthereafter similarly recedes therefrom. 1

The operation of successive cutting edges or teeth is showndiagrammatically in Figs. 6 to 11 of the drawings. It is assumed thatthe work W2 rotates in the direction of the arrow a and that the cutter56 rotates in the direction of the arrow b, so that the tool-engagingportion of the work moves downward while each work-engaging tooth of thecutter moves upward, V

The relations of the tool and cutter-are shown on a greatly enlargedscale in the diagrammatic views for the sake of clearness; If. theseviews were actually drawn to scale, the variations in diameter would betoo small to be detected.

The start of the cut of tooth No, 1 is substan tially'below the axis ofthe work, as indicated in Fig. 6, and with the tooth in this positionthe resultant diameter of the work is obviously'a maximum. f i

As the work and cutter rotate in the direction of the arrows sand 19respectively, tooth No. 1 moves upward to-the position shown in Fig. 7,where the edge 'of the cutting toothis at the shortest distance fromthe'axis of the work. During this upward movement of the tooth, the workhas rotated about one quarter of a revolution and the'diameter of theturned portion of the work has been graduallyreduced, asindicatedinFigfl; a

As tooth No. 1 thereafter continues its upward movement, the tooth movesfurther away from the axis of the work, thus gradually increasing thediameter of the work untilsaid tooth reaches the position indicated inFig. 8, where this tooth clears the work, thus ending its out.

By this time, however, tooth No. 2 has reached the position formedlyoccupied by tooth No. 1 (Fig. 6), with the work at substantially 180from the starting position. ToothNo. 2 then moves upward during about aquarter of arevolution of the work, from the'position shown in Fig; 9 tothe position shown in Fig. 10, and continues its upward movement duringthe next quarterof a revolution to -the-position shown in Fig. 11. Afull revolution-of the work isjthus completed, during which a desiredamount of; stock has been removed and the work has been given thenoncircular section indicated in Fig. 11. 7

Attention is again called to the fact, however, that the differencebetween the longest and shortest diameters is extremely slight and canhardly be detected except by calipering instruments.

As the tool slide 40 occupies a fixed position during the describedangular advance of the cutting teeth, and as the movements of both theWork and the cutter are rotary and continuous, the

parts may be rotated at any desired speed and the speed is not limitedby the weight or inertia of the parts, as in the usual relievingdevices.

If the end faces of the cutter teeth are in a plane perpendicular to theaxis of the work W,

there is a tendency for the tooth opposite the cutting tooth to drag onthe turned surface of the work, which may dull the cutter or mar theturned surface. To avoid this effect, the end of the cutter may beslightly crowned and the axis of the cutter may be placed at a slightangle to the axis of the work, as indicated in exaggerated form in Fig.12. I

If tapered or other formed shape of the finished Work is desired, atemplet bar 43 of a corresponding outline is provided. If straight workis to be produced, the bar 43 will be straight or may be replaced by ablock holding the tool slide 40 in fixed relation to the stand 33. V

By varying thespeed ratio between the cutter and the work spindle, anydesired number of longer or shorterdiameters or radii maybe produced,and the work may be given any desired number of high spots anddepressions. Having thus described my invention and-theadvantagesthereof, I do not wish to be limited to the details hereindisclosed, otherwise than as set forth in the claims, but what I claiznis: 1. Apparatus for producing non-circular work comprising meanstosupport and rotate a piece of work, a tool having a plurality ofcutting edges, and means to move said tool in timed relation to therotation" of the work, thereby successively causing said cutting edgesto move substantially in a plane parallel to the axis of the work and toeach successively approach and recede slightly from the work, and toadvance relative to the cutting'point, the rotary surface movement ofthe work being at a rate substantially greater than the'rate of movementof each cutting edge. 2; Apparatus for producing non-circular workcomprising means to support and rotate a piece of work, a tool having aplurality of cutting edges, and-means to move each cutting edgesubstantially in a plane parallel to a tangent'of'the work and in timedrelation to the rotation of the work, thereby successively causing saidedges to approach and recede from the work, thesu'riace' speed of thework being at a rate substantially greater than the rate of movement ofeach cutting edge.

3. Apparatus for producing non-circu1ar work comprising means to supportand rotate a piece of work, a tool having end cutting teeth, means tosupport said tool with its axis substantially perpendicular to the axisof the work, and means to rotate the tool and work in predeterminedtimed relation, .with the rotary speed of the work at least as great asthe rotary speed of the tool. 4. Apparatus for producing non-circularwork comprising means to support and rotateia piece vof work, a toolhaving end cutting teeth, means stantially intersecting said axis, andmeans to rotate said tool slowly and in timed relation to the rotationof the work, the rotary speed of the work being substantially greaterthan the rotary speed of the tool.

5. Apparatus for producing non-circular work comprising means to supportand rotate a piece of work, a. tool having end cutting teeth, a toolspindle having its axis substantially perpendicular to the axis of thework and substantially intersecting said axis, and a positive gearconnection between said work-rotating means and said tool spindle bywhich the tool is rotated in timed relation to the rotation of the workbut with a substantially slower rotary. motion, whereby said cuttingteeth successively and slightly approach and recede from the work.

6. The combination in apparatus for producing non-circular work as setforth in claim 5, in which said connections include a driving shaft forsaid spindle and a universal driving connection between said shaft andthe work-rotating means.

'7. The combination in apparatus for producing non-circular work as setforth in claim 5, in which said connections include a driving shaft forsaid spindle, a universal driving connection between said shaft and thework-rotating means, and'a. slidable connection between said drivingshaft and'said tool spindle.

8. Apparatus for producing non-circular work comprising means to supportand rotate a piece of work, a tool having endi cutting teeth, a toolspindle having its axis substantially perpendicular to the axis of thework and substantially intersecting said axis, and speed-reducingdriving connections between the work-rotating means and the cuttingtool, said connections including a worm gear on said spindle, a wormmeshing therewith, a driving shaft slidable in said worm, a countershaftgeared to said work-rotating means, and a universal connection betweensaid countershaft and said driving shaft.

9. Apparatus for producing non-circular work comprising means to supportand rotate a piece of work, a tool having a plurality of end cuttingteeth, a tool spindle having its axis substantially perpendicular to theaxis of the work and substantially intersecting said axis, means toefiect relative lengthwise travel between the work and tool, means torotate said spindle and tool at a rotary speed not greater than thespeed of the work and to thereby cause each cutting tooth V 'to moveslightly toward and from the axis of the work during each revolution ofthe work, and additional means to move said cutting tool bodily towardor away from the work during said relative lengthwise travel of the tooland work and in predetermined relation to said relative lengthwisetravel.

EDWIN R. SMITH.

